Abstract: An electrical outlet box is constructed in two sections adapted to be assembled together with one box section including an endwall and sidewalls extending from the endwall and terminating in free edges defining an open front with a plurality of elongated spike members rigidly mounted on the sidewalls and projecting outwardly from the open front in parallel spaced relation to one another, and the other box part is made up of a plurality of sidewall sections with an open front and back corresponding in size and shape to the open front of the first box section, and having guides adapted to engage the spike members to align the sidewalls of the two sections, with the guides and spike members cooperating to guide the two box sections into aligned relation whereby the sidewalls of the two box sections cooperate to define the sidewalls of the complete assembly.